How's my kitty? Acoustic parameters of cat-directed speech in human-cat interactions

In Western cultures, humans tend to use a specific kind of speech when talking to their pets, characterised, from an acoustical point of view, by elevated pitch and greater pitch modulation. Pet-directed speech (PDS), which has been mainly studied in dogs, shares some acoustic features with infant-directed speech (IDS), used when talking to young children. The purpose of this study was to test the hypothesis that adult humans also modify characteristics of their voice when talking to a cat. We compared acoustic parameters of speech directed to cats (CDS) and speech directed to adult humans (ADS). In a first experiment, we compared ADS and CDS utterances of male and female participants, addressing cats through video recordings, under controlled laboratory conditions. Both men and women used a higher pitch (mean fundamental frequency, or mean F0) in CDS vs. ADS. The second experiment was conducted under conditions allowing direct cat-human interactions, in a cohort of women. Once again, mean F0 was significantly higher in CDS vs. ADS. Overall, these data confirm our hypothesis that humans change the way they speak when addressing a cat, mainly by increasing the pitch of their voice. Further research is needed to fully investigate specificities of this speech.